1,721,244 research outputs found
Interaction between disinhibited bursting and fictive locomotor patterns in the rat isolated spinal cord
No full textUsing a transverse barrier that allowed discrete application of neurochemicals to certain lumbar regions of the rat isolated spinal cord, we studied the intersegmental organization of rhythmic patterns recorded extracellularly from ventral roots and intracellularly from single motoneurons. Fictive locomotor patterns were elicited by serotonin (5-HT) and/or N-methyl-D-aspartate (NMDA) or high K(+) solution applied to the rostral or caudal lumbar region of the cord. Neither 4-aminopyridine nor Mg(2+)-free solution shared this property. Coapplication of strychnine and bicuculline (blockers of fast synaptic inhibition) to the caudal part elicited slow bursting in the whole cord. These bursts could trigger episodes of fictive locomotion patterns in the rostral roots. When the rostral region was exposed to 5-HT and/or NMDA (during continuous application of strychnine and bicuculline caudally) a standard locomotor-like pattern was generated during each interburst interval and was surprisingly expressed with its typical pattern alternation even in the caudal area despite the local presence of strychnine and bicuculline. Midsagittal splitting of the caudal region did not change this alternating pattern, indicating that it was driven by rostral regions above the surgical cut. Discrete changes in the concentrations of NMDA rostrally modulated the burst amplitude recorded in the same region after caudal application of strychnine and bicuculline. The period of fictive locomotor patterns changed bimodally depending on the temporal relation with disinhibited bursts, indicating a tight interaction between these two rhythmic activities. These results are interpreted on the basis of a model that assumes a modular arrangement for the locomotor central pattern generator, made up by a series of unit burst generators with serial and crossed connections
Tire testing With a flat surface roadway simulator
No full text– 3th AIMETA International Tribology Conference, proceeding on C
Tire testing With a flat surface roadway simulator
No full text– 3th AIMETA International Tribology Conference, proceeding on C
Evidence for increased extracellular K+ as an important mechanism for dorsal root induced alternating rhythmic activity in the neonatal rat spinal cord in vitro
No full textAttentional Focus Effects on Lower-Limb Muscular Strength in Athletes: A Systematic Review
No full text: Pompa, D, Carson, HJ, Beato, M, di Fronso, S, and Bertollo, M. Attentional focus effects on lower-limb muscular strength in athletes: A systematic review. J Strength Cond Res 38(2): 419-434, 2024-Evidence links an athlete's focus of attention to enhancing strength performance. However, additional research is needed to investigate the applicability of studies beyond the tasks and population currently examined. Therefore, we aimed to systematically review studies concerning attentional focus effects on strength characteristics on lower-limb tasks in athletes. Scopus, Web of Science, and EBSCO databases were searched using PRISMA PERSIST guidelines and keywords related to the focus of attention, force production processes, and athletes. Subjects were categorized: world class (tier 5); elite (tier 4); highly trained (tier 3); trained/developmental (tier 2); nonathletes (tiers 1-0); and mixed (different levels). Fifteen of 296 studies met the inclusion criteria. Included studies investigated the focus of attention effects on performance ( n = 6), between skill levels ( n = 2), and for learning ( n = 5), with respect to subject preference ( n = 1); one study did not state the aim. Studies achieved an average risk of bias score of "excellent"; however, findings suffered in the assessment of certainty. Only 2 studies reported an advantage for one type of attentional focus (external focus) across conditions ( g = 0.13-0.42) with tier 2 and mixed tier athletes. Research does not address the needs of elite athletes, and there is limited evidence on each type of strength characteristics and muscle action. There is also a need to incorporate methodological steps to promote task-relevant instructions. Research should focus on contextualized information within professional practice to offer stronger translational implications for athletes and coaches
Alternating rhythmic activity induced by dorsal root stimulation in the neonatal rat spinal cord in vitro
No full text1. Electrical stimuli applied to a single dorsal root (DR) of the neonatal rat spinal cord in vitro were used to test the possibility that the central pattern generator responsible for locomotion could be activated by synaptic inputs.
2. Brief pulse trains evoked oscillatory patterns recorded from pairs of lumbar ventral roots. These patterns alternated rhythmically between the left and right sides and between predominantly flexor and extensor motoneuronal pools on the same side, thus displaying properties similar to the fictive locomotor pattern elicited by bath-applied excitatory transmitter agonists like NMDA and serotonin.
3. Usually pulse trains rather than single pulses were necessary to induce these patterns, the period of which was independent of stimulation frequency (1-10 Hz) and only moderately dependent on stimulus intensity.
4. Patterns reached a steady rhythm during the stimulus train, lasted for 50 +/- 20 s with gradual period lengthening and finally ceased.
5. Since DR stimuli activated the central pattern generator for locomotion in the rat isolated spinal cord, it is suggested that sensory inputs from the periphery can reach the spinal locomotor network and trigger its operation
Extracellular K+ induces locomotor-like patterns in the rat spinal cord in vitro: Comparison with NMDA or 5-HT induced activity
No full textBath-application of increasing concentrations of extracellular K+ elicited alternating motor patterns recorded from pairs of various lumbar ventral roots of the neonatal rat (0-2 days old) spinal cord in vitro. The threshold concentration of K+ for this effect was 7.9 ± 0.8 mM (mean ± SD). The suprathreshold concentration range useful to evoke persistent motor patterns (lasting ≤10 min) was very narrow (~1 mM) as further increments elicited only rhythmic activity lasting from 20 s to a few minutes. On average, the fastest period of rhythmic patterns was 1.1 ± 0.3 s. Intracellular recording from lumbar motoneurons showed that raised extracellular K+ elicited membrane potential oscillations with superimposed repetitive firing. In the presence of N-methyl-D-aspartate (NMDA) or non- NMDA receptor blockers [R(-)-2-amino-phosphonovaleric acid or 6-cyano-7- nitroquinoxaline-2,3-dione, respectively] extracellular K+ increases could still induce motor patterns although the threshold concentration was raised. Serotonin (5-HT) also induced alternating motor patterns (threshold 15 ± 7 μM) that were consistently slower than those induced by high K+ or NMDA. Ritanserin (1 μM) prevented the locomotorlike activity of 5-HT but not that of high K+ provided the concentration of the latter was further increased. Subthreshold concentrations of K+ became effective in the presence of subthreshold doses of 5-HT or NMDA, indicating mutual facilitation between these substances. The fastest pattern frequency was observed by raising K+ or by adding NMDA. In the presence of 5-HT, the pattern frequency was never as fast even if NMDA (or high K+) was coapplied. Furthermore, application of 5-HT significantly slowed down the K+- or NMDA-induced rhythm, an effect strongly potentiated in the presence of ritanserin. It is suggested that the operation of the spinal locomotor network was activated by rises in extracellular K+, which presumably led to a broad increase in neuronal excitability. Whenever the efficiency of excitatory synaptic transmission was diminished (for example by glutamate receptor antagonism), a larger concentration of K+ was required to evoke 1ocomotor-like patterns. The complex effect (comprising stimulation and inhibition) of 5-HT on alternating pattern generation appeared to result from a dual action of this substance on the spinal locomotor network
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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